Method of making diaphragms.



C. S. WICKES.

METHOD OF MAKING DIAPHRAGMS.

APPLICATION FILED SEPT. 20, 1912.

Patented Jan. 16, 1917.

2 SHEETS-SHEET 1.

INVEWTOR U/flfiezzae Mia/Z 65 A TTORNEV C. S. WICKES METHOD OF MAKING DIAPHRAGMS.

APPLICATION FILED SEPT. 20. 1912.

Patented; Jan. 16,1917

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MIJ'I'NESSES A TTORNEY iinirnn snares rarnirr onnicn.

CLAREIFTCE S. WICKES, 0F MERCHANTVILLE BOROUGH, NEW JERSEY, ASSIGNOR T0 VICTOR TALKING MACHINE COMPANY, A CORPORATION OF NEW JERSEY.

METHOD OF MAKING- DIAPHRAGMS.

To all whom it may concern:

Be it known that l, CLARENCE S. Wronns, a citizen of the United States, and a resi dent of Merchantville Borough, county of Camden, and State of New Jersey, have invented certain new and useful Improvements in Methods of Making Diaphragms,

of which the following is a full, clear, and

exact disclosure.

My invention relates particularly to diaphragms used in connection with acoustical instruments, such as talking machines, phonographs, gramophones and the like, and to the method of making the same, and the objects of, my invention are to produce a diaphragm which is strong, uniformly elastic, durable, homogeneous and which is unaffected by ordinary changes in temperature or humidity; to reduce the cost of diaphragms such as are used in acoustical instruments, and to be able to make a large number of diaphragms having substantially identical and uniform acoustical properties. A further object of my invention is to produce a diaphragm having the properties and characteristics above indicated, in a simple inexpensive manner, and by the performance of a comparatively few and simple steps.

A further object of my invention is to produce, by a molding or pressing process, a diaphragm which, when the process is completed, is substantially implastic and which permanently holds or retains the shape into which it has been formed.

A. further object of my invention is to form a diaphragm out of a material which is at first plastic or thermo-plastic, or capable of being molded, or made to flow, and during or substantially immediately after being molded or pressed, changes in physical and chemical properties, into an implastic, elastic, insoluble, substantially in-. fusible material, all of these latter properties being desirable in the completed diaphragm.

A further object of my invention is to produce a diaphragm comprising a thin vibratorv portion. unitarily or substantially integrally united. to a relatively heavy rim portion of material having similar characteristics to the said vibratory portion, and in which a radial tension may be produced Specification of Letters Patent.

Application filed September 20, 1912.

Patented Jlan. 1M8, llWi't. Serial No. 721,415.

upon or imparted to said thin vibratory portion.

A further object of my invention is to make a diaphragm, aving a rigid rim and a central vibratory portion, both composed substantially of final condensation or react1on products of phenol and formaldehyde but in which the final condensation product of the rim shrinks less or has a less tendencyto shrink under ordinary conditions than the final condensation or reaction product of which the thin central or vibratorv portion is composed, so that after the diaphragm has been formed, the shrinking of the thin vibratory portion to a greater extent or degree than the rim portion, will stretch or tend to stretch the central portion and will produce, or tend to produce a. substantially radial tension upon the thin vibratory portion of the diaphragm.

A further object of my invention is to produce a radial tension in the thin vibratory portion of a diaphragm, by employing the same condensation or reaction product of phenol or formaldehyde in both the rim and vibratory portion. but mixed or used in COllJlll'lCtlOIl with a different filler or body for the vibratory portion of the diaphragm than that used for the rim portion.

Other objects of my invention will appear in the specification and claims below.

Figure 1 is a perspective view of a disk, and a plurality of annuli or rings from which a diaphragm may be made; Figs. 2 and 3 are diametrical sections through the disk and rings when arranged in juxtaposition, the arrangement in Fig. 3 being a slightly different and modified arrangement from that shown in Fig. 2; Fig. 4. is a diametrical section of a die which is adapted to be used in the production of a diaphragm in accordance with this invention; Fig. is a diametrical section through a dia phragm, made in such a mold or die as is shown in Fig. 4; Fig. 6 is a plan view of the diaphragm shown in Fig. 5; Figs. 7, 9, l2 and 14- are sectional views through die or presses arranged to produce diaphragins of different shapes, and Figs. 8, 1O. 13 and 15 show the diaphragnis produced in the said dies respectively; Fig. 11 is a view of annuli or rings ranged juxtapose, and upon a disk or plate formed from sheets and arto be converted and changed into the diaphragm illustrated in Fig. 13 in the die or press shown in Fig. 12, and Fig. 16 is a sectional view of a further modified form of diaphragm.

In setting forth the invention forming the subject-matter of this application, an understanding of the same will probably be more readily had if the process be first described.

In carrying out the process, I first coat or impregnate a sheet of fibrous material, such as fabric, paper, blotting paper, sheets of fibrous pulp, or similar material, with a plastic, semi-plastic or thermo-plastic condensation or reaction product of phenol or its homologues, and formaldehyde or its polymers, with an alkaline base, or some equivalent or similar condensation or reaction product. One condensation product of phenol and formaldehyde, such as I have previously referred to and which readlly lends itself to the purpose of this invention, is bakelite. Bakelite is a well known commercial product and may be readily obtained either in solid form or in solution. The said sheet of fibrous material may be so coated or partially impregnated or thoroughly impregnated by immersing the same in a solution of said plastic reaction or condensation product, by painting the said sheet with said condensation or reaction product alone, or dissolved in a suitable solvent, or by flowing a solution of the same over said sheet. Acetone, amyl-acetate, alcohol and other suitable solvents may be used for obtaining a suitable solution of the said p1astic or thermo-plastic condensation or reaction product.

The sheet of fibrous material so coated or impregnated, is then dried. Thls coated or impregnated fibrous sheet is plastic or thermo-plastic; that is to say, it is moldable or impressible under the proper degree of heat and pressure, and it will flow within reasonable limits, when" subjected to heat and pressure, to conform to a mold. The sheet heretofore described by me may consist of a sheet of ordinary blotting paper coated or impregnated with bakelite or similar condensation product of phenol and formaldehyde. The said coated or impregnated sheet may then be subjected between plates, or in a die, to heat and pressure, preferably to a pressure of substantially 1500 pounds per square inch, at a temperature of substantially 340 degrees F., although it is to be understood that the pressure and temperature may vary when different though similarly acting materials, are employed. As a result of this treatment the coated, partially impregnated or thoroughly impregnated sheet undergoes marked physical and chemical changes. A further and different condensation product is formed from said plastic or miaeei thermo-plastic condensation or reaction product, under the application of heat and pressure, and the fibrous sheet of material becomes, if possible, more thoroughly impregnated with the said further condensation or reaction product of phenol or its homologues, and formaldehyde or its polymers, or of the materials originally used, which final condensation or reaction product is hard, elastic, implastic and unmoldable, glassy and substantially insoluble in any known solution. The sheet so impregnated with the said final condensation or reaction product will be found to be substantially homogeneous throughout, and translucent, if not quite transparent.

Diaphragms for sound boxes for talking machines or other acoustical instruments may be formed from the final sheet so obtained by cutting or punching disks from said sheet, which disks may be mounted in the sound box of talking machines in the same manner that the mica diaphragms are now ordinarily mounted in sound boXes.

Instead of cutting the diaphragms from the sheet after it has been subjected to heat and pressure, the disks may be cut from the sheet which has been coated or impregnated with the plastic or thermo-plastic condensation or reaction product and the disks so formed may be subjected to heat and pressure between dies or plates for the purpose of changing the said disks into disks of the final" implastic condensation or reaction product.

In carrying out the process above described, I may readily form diaphragms of any desired shape or configuration, and in the drawings are shown various forms and types of diaphragms produced by the process above indicated and set forth.

After the sheet of fibrous material has been impregnated or coated with the plastic or thermo-plastic condensation or reaction product, and dried, I may cut or stamp from said sheet disks 1 of substantially the size of the desired diaphragm, and I also cut or stamp from said sheet of fibrous material, rings or annuli 2, the outer diameter of which is substantially the same as that of the disks and I place one or more of said annuli on opposite sides of said disk, arranging said disks and annuli concentrically as shown in Fig. 1. So arranged and assembled, as shown in Fig. 2 I place the disks and rings within a mold or die, the surfaces between which are shaped to give the final desired shape to the diaphragm and subject the rings and annuli so placed in the mold to the desired degree of heat and pressure.

As a result of this treatment, the plastic or thermo-plastic condensation or reaction product is changed into a further and different condensation or reaction product in the manner above described, and during this change, the material interposed between the two sections of the mold will flow and fill the mold and take the shape given to it by the mold or die, and thus change into a material which will not flow orfuse or further change.

Referring to Fig. 4, when the superimposed rings and annuli shown in Figs. 2 and 3 are placed between the two parts 3 and at of the die 5, which parts 3 and t are provided with suitable rings or channels 6t$,

preferably opposite each other, and subjected to heat and pressure, the various layers which make up the structures shown in Figs. 2 and 3, will be integrally united and will form a single substantially homogeneous unitary diaphragm, such as is shown in Figs. 5 and 6. While being subjected to heat and pressure, the said plastic or thermo-plastic condensation or reaction product is changed into a further condensation or reaction product, and while the final product is being formed or just before the final product is formed, the material of the structures shown in Figs. 2 and 3 will flow and fill the space provided Within the mold 5.

While such a structure as is shown in Fig. 2 may-be treated in such a die as is shown in Fig. 4, to produce the diaphragm 7 shown in Fig. 5, the process may be facilitated and more easily carried out if the exterior diameters of the rings and the interior diameters of the rings 2 be made progressively smaller and larger respectively, so that the structure formed before treatment approximates the final desired form.

By the performance of the steps of the process above described, a diaphragm having a thin relatively flexible elastic non-fusible implastic interior or central portion 8, and an integral unitary hard inflexible rim portion 9, is readily formed from composite or built up structures such as are shown in Figs. 2 and 3.

While I have shown in Figs. 5 and 6 a diaphragm in which the thickened rim or edge 9 is substantially rectangular in cross section, the diagonals of the rectangle of the cross section being arranged normal to the plane of the diaphragm, it is to be understood that I do not limit myself to this particular form or shape. Thus, if it be deemed advisable to produce a diaphragm such as is shown in Fig. 8, the composite structure shown in Fig. 2 may be pressed in such a die as is shown in Fig. 7 and simultaneously heated, or if such a diaphragm as is shown in Fig. 10 is to be produced, a composite structure similar to that shown in Fig. 3 may be placed between the halves of the die shown in Fig. 5) and similarly pressed.

If it is desired to make a diaphragm hav-- ing an integral flange upon one side thereof only, such as is shown in Fig. 13, a series of narrow rings or annuli cut from the sheet between the halves of impregnated with the said plastic or ther- "mo plastic condensation or reaction product are arranged juxtapose and superposed upon the disk 1, to form a limited ring or wall or flange, and then placed within the die shown in Fig. 12, and subjected to heat and pressure. It is further to be understood that when a plain diaphragm similar to the plain mica diaphragms commonly used in the sound boxes for talking machines is to be produced, a plain disk 1 may be placed such a die as is shown in Fig. 14, and subjected to heat and pressure, with the result that the plain diaphragm shown in Fig. 15, will be readily produced. As has been indicated above, however, the entire sheet of fibrous material coated, impregnated or partially impregnated with the said plastic or thermoplastic condensation or reaction product may be subjected between plates to the desired pressure and temperature, and the whole sheet changed or transformed into the said implastic condensation or reaction product, and from this said latter sheet finished diaphragms, substantially identical with that shown in Fig. 15, may be cut or punched in any desired way.

The diaphragm shown in Fig. 16 is of the same general type as illustrated in Figs. 5, 8 and 10 above described, except that the thickness of the flexible portion 8, adjacent the rim 9, is reduced, as at 10, in order to make the central portion 8 more flexible, vibratable or yielding, and more readily acted upon by the slight impulses produced by sound waves.

A diaphragm produced by the process above described will be a substantially homogeneous integral structure, notwithstanding the fact that a plurality of layers or thicknesses of material may have been used in making the same, and the rim or flange will be integral with the body or flexible portion thereof. Moreover, the finished diaphragm being impervious to moisture and implastic and infusible, will not be aifected by changes in temperature or atmospheric conditions, and will therefore retain the shape into which it has been finally pressed.

It is to be understood that my invention is not to be construed as limited to the exact materials above described or referred to, nor to the exact pressures and temperatures indicated, since the same may vary Within reasonable limits, and my invention contemplates the making of diaphragms out of any material which, during the initial stage of its treatment may be shaped or molded, and which, after changed in its chemical and physical properties into substantially implastic material, and I have used the expression plastic con; densation or reaction product of phenol and formaldehyde to signify broadly any contlltl taking the desired shape,

&

densation or reaction-product of phenol or its homologues, or any material similar to phenol, with formaldehyde or its polymers, or any material similar to formaldehyde, or any similar plastic condensation or reaction product, which is moldable or impressible with or without the application of heat or pressure thereto; the expression thermoplastic to indicate the property or quality of a material as a result of which the material may be molded or impressed, or made to flow when subjected to heat or to heat and pressure; and the expression implastic condensation or reaction product of phenol and formaldehyde to signify broadly, and substantially implastic or unmoldable condensation or reaction product produced by a further condensation of the said plastic product, preferably by the application thereto of heat or pressure, or both. It is also to be understood that the fibrous material which is originally impregnated or coated with the plastic condensation or reaction product, acts mainly as a body or filler, and if it is so desired, may be omitted and the original sheets may be formed out of the plastic condensation or reaction product alone. In practice, however, I prefer to use a body or filler of fibrous material.

Numerous condensation or reaction products of phenol and its homologues, and formaldehyde or its polymers, or similar materials, may be found on the market, and I therefore, do not wish to limit myself to any particular one of them. For illustrative purposes, however, I might state that the condensation product of phenol and formaldehyde, known commercially as bakelite, is one and among those condensation or reaction products which may be used by me in the diaphragm described above, and the method of making the same.

In a diaphragm made in the manner and of the material before set forth, with a difference in the surface area per unit mass between the thin vibratory portion and the rim portion, there may be a tendency of the thin vibratory portion to shrink slightly, and to a greater degree than the heavy thicker unitary substantially integral edge or rim, and the degree or extent to which one of the said two parts may shrink with respect to the other may be greatly modified or affected by the use of different amounts or proportions of the vegetable, animal, or mineral fiber used with the different plastic or thermo-plastic condensation or reaction products. In other words. the amount of shrinkage in a finished diaphragm may be made to depend a great deal upon the particular filler and the particular plastic or thermo-plastic condensation or reaction product and the particular proportions of each employed.

Certain proportions of one to the other will produce a structure in which there is substantially no shrinkage, whereas certain other proportions of these materials will result in a product which may shrink or tend to shrink quite a. deal. Therefore, by making the thinner vibratory portion of a composition containing one particular filler with a certain amount of the plastic or thermo-plastic or other condensation or reaction product. and by making the thick or heavy rim of another filler with the same or other proportions of' the same or other plastic or thermo-plastic condensation or reaction products, the amount of shrinkage in or the tendency to shrink of the said thin vibratory portion, may be greater than that of the heavier rim, and this difference in shrinkage of the two parts of the diaphragm, or the tendency of one to shrink to a greater extent than the other may be made to produce a radial tension or stretch of the thin vibratory portion when such tension is desired. If, on the other hand, however, it be desirable to impart or impose substantially no such tension upon the thin vibratory portion, different materials or different proportions of the above indicated ingredients may be employed for the vibratory portion and for the rim, so that the shrinkage of both of the said parts of the finished diaphragm will be the same, or so that there will be no relative shrinkage of either of said parts with regard to the other.

This shrinking of the diaphragm may in some cases, be effected or modified by an aging of the same, but after the finished diaphragm has assumed 1ts final condition,

'the composition will remain substantially stable and the finished product will be unaffected by heat, moisture or other atmospheric changes or conditions. The diaphragms so made will not warp nor twist in their final form, which characteristic is also desirable in this kind of a structure.

The diaphragms above described possess qualities which make them particularly adapted for the sound boxes for sound reproducing machines and for other acoustical instruments. Thus, the low specific gravity of the condensation products above referred to (about 1.25) as compared with that of glass, mica, or the metals, gives them a small vibrating inertia. Their resiliency is of a peculiar nature, very different from the elasticity of rubber, and it is of that type which makes them particularly well suited for the reproduction of sound. The facility with which various fibrous substances or other suitable materials may be incorporated into the structure of the diaphragm permits of a predetermined variation in specific gravity. vibrating inertia, texture and general and chemical and acoustical properties. A further quality or characteristic of the said diaphragms resides in :warp, or become distorted. above set forth, shrinkage of the finished the use of the tially upon reduce the cost of the completed diaphragm.

While broadly my invention is independent of any particular form or shape of diaphragm, the preferred form embodies in its construction a relatively heavy rigid and strong rim or edge, as indicated in Figs. 5, 8, 10, 13 and 16, as such a rim or edge tends to make the entire structure stiff or self supporting, and to hold the flexible or vibratable portion 8 taut or in a fixed plane, and further tends to overcome or offset any tendency of the diaphragm as a Whole to As has been diaphragm or .the tendency to shrink, or change in its size, can be greatly modified and, if desired, substantially overcome by proper amount or proportion of vegetable, animal or mineral fiber or filler with the particular plastic or thermo-plastic condensation or reaction product employed. In other Words, the amount of shrinkage in a finished diaphragm will depend substanthe particular filler, and the particular plastic or thermo-plastic condensation or reaction product, and the particular proportions of the same which are employed, and certain proportions of one to the other are found to result in a structure in which the shrinkage is very small or practically nothing. These properties or qualities, therefore, enable one to construct a substantially uniform homogeneous integral diaphragm in Which the central or vibratory portion may be made to have substantially no radial tension, or, if so desired. may be made to have a substantially predetermined radial tension imparted thereto.

Having thus described my invention, What I claim and desire to protect by Letters Patent of the United States is:

1. The method of making a diaphragm for acoustical instruments which consists in impregnating asheet of fibrous material With a thermo-plastic condensation product of phenol and formaldehyde in solution, forming a disk from the same, superposing upon the edge portion of said disk an annulus of similarly impregnated sheet material, subjecting said disk and annulus to heat and pressure to change said condensation product into a further condensation product and to form thereby an integral homogeneous infusible implastic diaphragm, having a. stiffening rim.

2. The method of making a diaphragm for acoustical instruments which consists in impregnating a sheet of fibrous material with a thermoplastic condensation product of phenol and formaldehyde in solution, forming a disk from the same, superposing upon the edge portion of said disk an annulus of similarly impregnated sheet material, subjecting said disk and annulus to heat and pressure in a mold to further condense said condensation product, and to form thereby an integral homogeneous infusible implastic diaphragm having a stiff substantially integral rim.

3. The method of making a diaphragm formed from sheets of material similarly impregnated and subjecting said disk and annuli to heat and pressure to further condense said condensation or reaction prodact and to form thereby an integral homogeneous infusible implastic diaphragm hav ing a stiff substantially integral rim.

4 The method of making a diaphragm for acoustical instruments which consists in impregnating a sheet of fibrous with a condensation or reaction product of phenol and formaldehyde, forming a disk from the same, super-posing upon the edge portion of said disk a plurality of annuli formed from sheets of material similarly impregnated, and subjecting said disk and annuli to heat and pressure in a mold to further condense said condensation product and to form thereby an integral homogeneous infusible implastic diaphragm having a stiffening rim at the edge thereof.

The method of forming a diaphragm for acoustical instruments which consists in impregnating a sheet of fibrous material with athermo-plastic condensation or reaction product of phenol and formaldehyde, forming a disk from the same, placing upon the opposite faces of said disk and adjacent the edges of the same, a plurality of superposed annuli formed from sheet material similarly impregnated, subjecting said disk and annuli to heat and pressure in a mold conforming generally to the form of said superposed disk and annuli to change the form of said material to that of the mold and to change said condensation product into an implastic product, thereby to form an integral homogeneous infusible implastic diaphragm, having a stiff substantially integral rim.

material j product of phenol and formaldehyde, formlng a posite edges of the same, a plurality of superposed annuli formed from sheets of material similarly impregnated to approximate the final form of diaphragm desired, subjecting said disk and annuli to heat and pressure in a mold and thereby changing said plastic condensation or reaction product into an implastic condensation or reaction product of phenol and formaldehyde, distributed substantially homogeneously throughout the diaphragm so formed.

disk from the same, placing upon op- 7 A method of forming a diaphragm for.

acoustical instruments, which consists in forming a disk composed substantially of a condensation or reaction product of phenol and formaldehyde, superposing upon the peripheral portion of said disk an annulus composed substantially of a condensation or reaction product of. phenol and formaldehyde, and subjecting said disk and annulus to heat and pressure to simultaneously change said condensation product into a further condensation or reaction product and to substantially integrally unite said annu lus and disk.

8. A method of forming a diaphragm for acoustical instruments, which consists in forming a disk composed substantially of a condensation or reaction product of phenol and formaldehyde, superposing upon the peripheral portion of said disk an annulus composed of a condensation or reaction product of phenol and formaldehyde, subjecting said disk and annulus to heat and pressure to simultaneously change said condensation product into a further condensation or reaction product and substantially integrally unite said disk and annulus, and aging the product so formed.

9. A method of forming a diaphragm for acoustical instruments, which consists in forming a disk composed substantially of a condensation or reaction product of phenol and formaldehyde and a filler, superposing upon the peripheral portion of said disk an annulus of a material composed of a confaces of said disk and adjacent the ucts, and to simultaneously integrally unite said annulus and disk.

10. A method of forming a diaphragm for acoustical instruments, which consists in forming a disk composed substantially of a condensation or reaction product of phenol and formaldehyde and-a filler, superposing upon the peripheral portion of said disk an annulus of material composed of a condensation or reaction product of phenol and formaldehyde and, a filler, and subjecting said disk and annulus to heat and pressure to simultaneously change said condensation products into further condensation or reaction products, and to substantially integrally unite said: diskand annulus, the final condensation or reaction product of said disk having a greater tendency to shrink than the final condensation or reaction prod- 7 not of said rim.

11. A method of forming a diaphragm for acoustical instruments, which consists in forming a disk composed substantially of a condensation or reaction product of phenol and formaldehyde and a filler, superposing upon the-peripheral portion of said disk an annulus of material composed of a condensation or reaction product of phenol and formaldehyde and a filler, and subjecting said disk and annulus to heat and pressure to simultaneously change said condensation products into further condensation or reaction products, and to substantially integrally unite said disk and annulus, the final condensation or reaction product of said rim being substantially non-shrinkable, and the final condensation or reaction product of said disk having a tendency to shrink.

In witness whereof, I have hereunto set my hand this 18th day of September. 1912.

CLARENCE S. WICKES. Witnesses:

FRANK B. MIDDLETON, J r., CHARLES F. WILLARD. 

